A group of experts has called for the creation of a national system to assess how drug addicts are treated to discover if the help they receive is effective.

Despite more than 22,000 Scots receiving the heroin substitute methadone, research published yesterday found that there is little effort to find out whether that is working.

It was part of a package of findings published by the Scottish Executive which confirmed the liquid substitute for heroin, which is itself highly addictive, remains at the centre of efforts to help people away from their addiction.

However, it was concluded that a national system to keep track of the way methadone is prescribed should be set up as a matter of urgency.

Of the people who receive the prescribed drug to help them treat their addiction to heroin, about one third of all users have children aged under 16 who are living with them. Around half the addicts take methadone under supervision, often in a pharmacy. More than 1000 are in prison.

The survey was commissioned by former first minister Jack McConnell in response to the death of two-year-old Derek Doran, from East Lothian, in December 2005, who drank the methadone which had been supplied to his mother.

The research has found that many of those who use methadone report it has made a strong positive impact on their previously chaotic lifestyles. Among the responses from those using the treatment, comments included: "It takes the madness out of your lifestyle".

Another said: "Methadone isn't the answer but it is the start of the answer."

Among the benefits were that it helps gain stability in their lives, improving relationships and ability to care for children, improved finances, self-respect and it was a help in moving into education and employment.

The report by the Scottish Advisory Committee on Drug Misuse (SACDM), an expert group of clinicians and academic experts, found services are "rarely evaluated objectively".

Fergus Ewing, the community safety minister, is due to chair a meeting of the advisory committee today to discuss the report's findings. He said: "The report makes clear there are areas of concern about the use of methadone. Tackling those areas is a key priority for us. That means improving integration of methadone treatment with extra support."